The present invention relates to a signal processing technique for decoding/outputting an encoded bit stream and outputting a digital signal.
When decoding/outputting of an encoded bit stream and outputting of a digital signal is performed, for example, processing such as decoding and outputting are performed by a signal processor shown in FIG. 10.
FIG. 10 is a block diagram illustrating a known signal processor. As shown in FIG. 10, in the known signal processor, a video bit stream (referred to as “video stream” for short in FIG. 10), i.e., encoded picture data is received by a picture input section 2001, external data, i.e., analog data or digital data is received by an external data buffer 2005. The video bit stream received by the picture input section 2001 is temporarily held by a video stream buffer 2002, decoded by a video decoding section 2003 and then displayed on a picture display section 2004. Next, the video bit stream is output from the picture display section 2004 to a blending section 2006. Moreover, the external data received by the external data buffer 2005 is also output to the blending section 2006. In the blending section 2006, then, the decoded video bit stream and the external data are synchronized with each other and displayed. Note that as the external data, for example, data in accordance with the BT 656 standard is used.
On the other hand, the audio bit stream is received by an audio input section 2008 and PCM (pulse code modulation) audio data corresponding to external data is received by an audio buffer 2012. An audio bit stream is temporarily held by an audio stream buffer 2009 and then decoded by the audio decoding section 2010. Thereafter, a sound is output from an audio output section 2011. Moreover, the audio data received by the audio buffer 2012 is output as an audio output from an audio output section 2013.
Moreover, it normally requires a longer time to decode the video bit stream than it does to decode the audio bit stream. Therefore, in the known signal processor, a synthesizing section 2007 is provided so that a display of the video bit stream and an audio output of the audio stream are synchronized with each other. However, in a known technique, processing is performed without synthesizing the external data and the audio data. An example of such signal processors is disclosed in Japanese Laid-Open Publication 2001-506450.